| 摘要 |
PURPOSE: An output buffer is provided to secure a stable operation by minimizing a driving capacity variation of pull-up and pull-down transistors according to an operation voltage variation. CONSTITUTION: An output buffer comprises a pull-up and pull-down driving part(200), a control part(220), a pull-up node control part(240) and a pull-down node control part(260). The pull-up and pull-down driving part(200) consists of a PMOS transistor(PM2) and an NMOS transistor(NM2), and drives an output terminal(dout2) in response to a voltage level value of a pull-up node(dp2) or a pull-down node(dn2). The pull-up node control part(240) controls the pull-up node(dp2) and the pull-down node(dn2) in response to an enable signal(enable) of an output buffer and data(out_data) inputted to output through the output buffer. The pull-up node control part(240) controls a voltage level of the pull-up node(dp2) in response to a voltage level value of the output terminal(dout2) and a power supply voltage(Vcc) in order to maintain a driving capacity of the PMOS transistor(PM2) regardless of a Vcc variation constantly. The pull-down node control part(260) controls a voltage level of the pull-down node(dn2) in response to a voltage level value of the output terminal(dout2) in order to maintain a driving capacity of the NMOS transistor(NM2) regardless of a Vcc variation.
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